Will the Periodic Table Ever Be Complete?

The last time I studied the periodic table was high school chemistry, and since then, more elements have been added to the iconic, colored chart of chemical elements. After scientists recently discovered four new elements, some experts have said the periodic table is now complete. But this video by SciShow questions that assumption.

Though scientists have discovered the elements up to number 118, no one can be sure of whether or not there are remaining elements to add to the periodic table. In modern science, elements are measured by weight, and it's believed that there's a maximum atomic number or atomic weight possible for atoms.

Chemist Elliot Quincy Adams predicted that no element could have an atomic weight larger than 256. Today, however, elements are measured by their atomic number, which is the number of protons in the nucleus. But in 1911, the days of Adams, protons hadn't been discovered yet. There were also various different periodic tables (not one master table like we have today), so Adams proposed a new table that would end with an atomic weight of 256, or the equivalent to an atomic number of 99 or 100. However,, scientists have since made the next higher 18 elements, rendering Adam's 256 end element moot.

Chemist Richard Feynman also predicted that there would be an end to the periodic table. He calculated that an atom with 137 or more protons would violate "special relativity," and would need electrons to stabilize a positive charge packed together in the nucleus. Because more protons in the nucleus means more force pulling electrons in, electrons would have to go faster and faster the bigger the nucleus gets—at a certain point, they'd have to go faster than the speed of light which is impossible.

It turns out that Feynman's calculation was incorrect, however, and when his calculation is correctly repeated, the element would be up to 173 (instead of 137). Yet, the higher elements get the more unstable they become, which would make them impossible to exist for more than a fraction of a second, if at all.

Physicists, however, have predicted "islands of stability," meaning that some elements are more stable than expected, based on their structure. The first island of stability would start around 122 or 126—not too far from the most recently discovered, 118. So hey, the periodic table may not be complete, after all.